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**Subject**: **Re: Unexpected calculation result with Lua53**
**From**: Jay Carlson <nop@...>
**Date**: Mon, 4 May 2015 14:37:36 -0400

On May 4, 2015, at 11:56 AM, Roberto Ierusalimschy <roberto@inf.puc-rio.br> wrote:
> I must confess I learned something new from this discution. From now
> one, whenever I teach the factorial function in C, I will write it like
> this:
>
> double fact (double n) {
> double a = 1;
> while (n > 0) a *= n--;
> return a;
> }
>
> After all, it gives "better" results then the old-fashioned version :-)
Down vs up is fun.
> n=1 for i = 1,80 do n = n * i end print(n) n1=n
7.1569457046264e+118
> n=1 for i = 80,1,-1 do n = n * i end print(n) n2=n
7.1569457046264e+118
> return n2-n1
1.7917957937422e+103
Only a few googols of difference....